Ok if you are using a custom ui move the "eq2ui_mainhud_welcome.xml" file to your custom UI folder (ie eq2maps ect..)
Then open up the .xml you just copied (not the original) in an editor of some sort (notepad or wordpad are fine)
Then find this, it should be at the very top
<Page Activated="true" eq2opensound="ui_window_inventory_open" eq2usescomwndcontrols="false" IgnoreTab="false" Location="112,72"
MaximumSize="1024,1024" Name="Welcome" PackLocation="center,center" ScrollExtent="820,600" Size="820,600" UserMovable="true" UserScrollable="false" version="2.0">
And change the bolded part to
MaximumSize="0,0"
and it should look like
<Page Activated="true" eq2opensound="ui_window_inventory_open" eq2usescomwndcontrols="false" IgnoreTab="false" Location="112,72"
MaximumSize="0,0" Name="Welcome" PackLocation="center,center" ScrollExtent="820,600" Size="820,600" UserMovable="true" UserScrollable="false" version="2.0">
Save your file and no more welcome screen... (at all, even if you want to actually look at it later lol)